Options Assessment Report A816 - Appendix 1
Argyll and Bute Council · 11 September 2025
Back to Environment, Development and Infrastructure Committee — 11 September 2025 and its agenda
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Options Assessment Report A816 Bealach Mor February 2025
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2 Options Assessment Report A816 Bealach Mor Project no: GLJ620 Document Title: Options Assessment Report; A816 Bealach Mor Revision: Rev1 Document Status: DRAFT – For comment Date: 03/04/25 Client: Argyll and Bute Council Project Manager/Director: N. McLean Author: N. Horsburgh Document history and status Revision Date Description Author Checked Approved Draft Rev 0 17/02/2025 Draft for Client Comment N.H N.M N.M Draft Rev 1 03/04/2025 Draft for Client Comment N.H N.M N.M Contents 1. Introduction ................................................................................................................... 3 2. Existing Conditions ...................................................................................................... 6 3 Option Generation ...................................................................................................... 15 References .............................................................................................................................. 32 APPENDIX A ......................................................................................................................... 33
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3 Options Assessment Report A816 Bealach Mor 1. Introduction 1.1 Background The A816 through Bealach Mor is a main A class road in Argyll and Bute on the west coast of the Scottish Highlands. The road is the main connection route between Oban and Lochgilphead. The road runs along the northern slope of Creag nam Fitheach (214m), A’ Bheinn (246m). On the 7th October 2013 as a result of exceptional rainfall, the wettest 2-days in series from 1891, with 100-150mm rain falling widely across Southern and Central Highlands (Kendon, 2023). Approximately a month of rainfall fell in a 36-hour period in a number of areas within Argyll and Bute. The heavy rainfall fell onto already saturated ground and triggered 3no. separate but closely spaced debris flow events (wet saturated landslides that flow) from the steep slope immediately adjacent to the A816. This deposited approximately 6000 tonnes of material over nearly 200m length of road, with more debris on the surrounding slopes and fields. Clearance works removed an estimated 10,000 tonnes of debris, from the original event and subsequent debris from later smaller events and erosion / wash out of material remaining on the slope. Further assessments of the slope during and following clearance highlighted an ongoing risk of further movement in the landslide areas and a hazard from precarious boulders and potential for rock fall from previously and newly exposed rock scarps high above the road. Scaling works (removal of loose rock and boulders) was undertaken on the slope above the road as far as practicable, but the works required to lower the rockfall risk further involved significant engineering works. More boulders continue to be exposed and weather out from the landslide scarps and deposits following rainfall which washes out soil covering them and holding them in place. Owing to the ongoing movement and potential for further blocks and/or debris to impact the road a temporary bypass route was constructed as the fastest and safest way to reopen the A816. The bypass as opened to the public on the 16th December 2023, following 6 weeks of construction (Figure 1). Due to landowner, environmental, engineering and archaeological challenges and constraints the temporary road is built in a restricted narrow corridor resulting in a single lane with passing places, open ditches with steep side drops, a sharp corner and very steep incline at the western side. Built as a temporary road, i.e., not to highway standard, the road is approximately 320m length and the alignment was chosen to follow existing track and foundation of the military road to minimise foundation and subsidence issues. The road is constructed to Forestry Land Scotland specification (as a floating road), as far as practicable, with a covering of asphalt.
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4 Options Assessment Report A816 Bealach Mor Figure 1 – Aerial image of the temporary bypass and A816 (south), taken 17/07/24. 1.2 Purpose of this report The purpose of this report is to document the development and assessment of options for the permanent road and to consider the scheme objectives, value, engineering/geohazards, environmental/archaeological, advantages, disadvantages and constraints of the options considered. The DMRB is a collection of documents used to provide requirements and advice for works and developments of motorways and trunk roads. Although not strictly applicable to the replacement/upgrade of the section of the A816 at Bealach Mor, it is useful guidance for Argyll and Bute Council road schemes, although not all of the documents may be applicable. The DMRB guidance TD 37/93 ‘Scheme Assessment Reporting’ has been withdrawn, and while is no longer formally used the three stages of assessment are still commonly referred to as a useful points of reference. This report aims to include the main elements form Stage 1 (Strategic assessment) and Stage 2 (Route option assessment). As many of the environmental, engineering and economic constraints for the area were investigated (along with consultation of SEPA, HES/WoSAS, Argyll and Bute Council, Landowners, Tillhill) during the temporary bypass route the knowledge was utilised for the gathering of the options assessment. It is suggested that once the options are identified in this report and preferred option is determined, that further consultation will be required with the relevant bodies/parties as well as wider public consultation. This report is restricted to the assessment of the proposed route areas, it should be noted that geotechnical hazards remain outwith the immediate study area, particularly along the A816 westwards from Kintaraw towards Salachary. 1.3 Strategic decisions The A816 is a main arterial route in Argyll, local communities and deliveries etc., facing large detours with social and economic impacts to communities of the road being closed.
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5 Options Assessment Report A816 Bealach Mor Following assessment of the landslide site it became clear that a prolonged closure was going to be required to remediate the landslide site. The temporary bypass was the preferred option chosen by Argyll and Bute Council to allow traffic to bypass the works and for stabilisation works to continue unhindered. The route was chosen as the fastest to deliver with minimal preparatory works. Transport Scotland’s vision for Scotland’s transport system for the next 20 years includes four interconnected priorities: Reduces Inequalities, Takes Climate Action, Helps Deliver Inclusive Economic Growth and Improves our Health and Wellbeing. Argyll and Bute Council’s economic strategy and climate action plans address environmental challenges, including those related to climate change and natural disasters, such as landslides. Argyll and Bute Council’s refreshed economic strategy for 2024-2034 focuses on resilience and adaptation to climate change, which includes mitigating risks from severe weather events. The STPR2 report (Jacobs, 2020) documents and discusses the current planning and transport strategy for transport in detail, the reader is referred to this document for further reading.
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6 Options Assessment Report A816 Bealach Mor 2. Existing Conditions 2.1 A816 Bealach Mor Scottish Government 6-fold Urban Rural Classification 2016 and 8-fold Urban Rural Classification 2016 classes the Bealach Mor area as Remote Rural and Very Remote Rural respectively. 2.2 Land use • Residential The area for all options considered is rural with no residential properties within the assessment area. • Commercial (Agricultural) Land The area is shown on the Land Capability for Agriculture in Scotland mapping (1:250,000) as Class 6.1: Land is capable of only rough grazing due to intractable physical limitations; the semi-natural vegetation provides grazing of high value. There is a commercial forestry planation managed by Tillhill to the north of the existing A816. The temporary bypass follows an existing forestry road through the south side of the plantation. • Development Land There are no areas of development or active planning applications within the assessment area. 2.2 Environment SNH Landscape Character Type lists the area as Type 43 upland parallel ridges – Argyll. The landscape comprises a distinctive series of linear ridges aligned in parallel with the south- west/north-east grain of the coast with key characteristics listed below: • Upland landscape of long, parallel ridges and narrow, linear lochs and glens. • Tightly packed ridges follow a south-west/north-east alignment. • Steep, sharp ridge-tops, with dramatic rocky outcrops. • Extensive conifer forests. • Deciduous, largely ancient oak woodland on steep, sheltered slopes of ridges and on loch edges. • Small marginal pastures or moorland in isolated patches between the un- forested ridges. • Dramatic, scenic upland landscape. Habitats within the wider area are mixed with large areas of woodlands and open moorland / grazing. The limit of the desktop search for protected species including badger, otter, pine marten and red squirrel has been kept at 2 km from the site. Bats and trees and their foraging routes are more complex. The zone of influence for bats has been set at 10 km as
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7 Options Assessment Report A816 Bealach Mor they are a mobile species which can be influenced by habitat fragmentation. Otters have been scoped out of the surveys as there are no watercourses (streams, ditches) nearby. Designated sites will not be affected by the proposed development due to the topography and surrounding habitats adjacent to the site however the zone of influence has been set at 2 km for a desktop search. There are no protective designations within 2 km of the bypass, this would include the areas for all route options assessed. A search of the National Biodiversity Network Gateway (NBN) was made for protected species within 2km of the bypass (10km for bats), the results are presented in Table 1 below. Table 1 – NBN protected species results Common Name Scientific Name Badger Meles meles Otter Lutra lutra Pine marten Martes martes Red squirrel Sciurus vulgaris Soprano pipistrelle Pipistrellus pymaeus • Phase 1 Habitat Survey A Preliminary Ecological Appraisal report, including a Phase 1 Habitat Survey was undertaken for the proposed area (Preston, R., 2025). The standard methodologies (as found in the ‘Handbook for Phase 1 habitat survey - a technique for environmental audit, 2010 JNCC) was used. A map was produced at a scale of 1:1,000 (Appendix I, Phase I Habitat Survey). The Phase 1 Habitat Classification and associated field survey technique provide a standardised system to record semi-natural vegetation and other wildlife habitats. The approach is designed to cover large areas of countryside relatively rapidly. It presents the user with a basic assessment of habitat type and potential importance for nature conservation. Each habitat type/feature is identified by way of a brief description of its defining features. It is then allocated a specific name, an alpha-numeric code, and unique mapping colour. Important findings are recorded as target notes and may identify areas which require more in-depth study.
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8 Options Assessment Report A816 Bealach Mor Figure 2 – Phase 1 Habitat results and Route Options (Preston, R., 2025). Phase 1 Habitat Survey Results Results are summarised in Figure 2, the full Preliminary Ecological Appraisal report is attached within Appendix A A1.1.2 Plantation broadleaved woodland This habitat is found at the eastern extent of the route adjacent to the A816 on the east side of the route and contains young sessile oak (Quercus petraea). A1.2.2 Conifer plantation Approximately halfway along the proposed grey route it is bounded on either side by commercial conifer forests with predominantly Sitka spruce (Picea sitchensis), occasional Japanese larch (Larix japonica), occasional Scots pine (Pinus sylvestris) and edged with Goat willow (Salix caprea), Grey willow (Salix cinerea) and Downy birch (Betula pubescens). The age of the forest is at pole stage with severe windblow after the recent storm. The forest is dense with no understorey. A2.1 Dense continuous scrub The area between the A816 and the western end of the route has a band of continuous scrub including; Downy birch, Hawthorn (Crataegus monogyna), Rowan (Sorbus aucuparia), Bramble, Bracken and Gorse (Ulex europaeus). B1.2 Semi-improved acid grassland This habitat is found from the western edge of the conifer plantation to where it meets the dense scrub adjacent to the A816 and from the eastern edge of the conifer plantation along the wayleave and has the following species present; Bracken (Pteridium aquilinum), Bramble (Rubus fruticosus), Creeping buttercup (Ranunculus repens), Foxglove (Digitalis
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9 Options Assessment Report A816 Bealach Mor purpurea), Purple moor grass (Molinia caerulea), Scaly male fern (Dryotperis affinis), Sharp-flowered rush (Juncus acutiflorus), Soft rush (Juncus effuses), Tormentil (Potentilla erecta), and Tufted hairgrass (Deschampsia cespitosa). B5 Marshy grassland This habitat is found at the east end of the route next to the A816 and ends at the bottom of a slope to the north west where the land rises to the wayleave and has scattered small scrubby trees. The wetness likely results from seepage from the stream. The National Vegetation Classification for this habitat is M28 Iris pseudacorus - Filipendula ulmaria mire. Blunt-leaved bogmoss (Sphagnum palustre), Bracken (Pteridium aquilinum), Bramble (Rubus fruticosus), Creeping buttercup (Ranunculus repens), Flag iris (Iris pseudacorus), Foxglove (Digitalis purpurea), Goat willow (Salix caprea), Hawthorn (Crataegus monogyna), Purple moor grass (Molinia caerulea), Sitka spruce (Picea sitchensis), Soft rush (Juncus effuses), Tormentil (Potentilla erecta), Tufted hairgrass (Deschampsia cespitosa) and Wild angelica (Angelica sylvestris). D5 Dry heath / acid grassland mosaic This habitat is found on the ride going through the conifer plantation. Bank haircap moss (Polytrichum formosum), Blaeberry (Vaccinium myrtillus), Bracken (Pteridium aquilinum), Common heather (Calluna vulgaris), Downy birch (Betula pubescens), Goat willow (Salix caprea), Greater wood-rush (Luzula sylvatica), Hard fern (Blechnum spicant) and Purple moor grass (Molinia caerulea). No invasive species were observed in any of the survey areas. Further detail on the habitats found in each route area are included with the route options for ease of reference. Protected Species Results • Otter No otter holts or rest ups were found within the survey areas. • Badger No signs of badger were found. • Pine marten No pine marten dens were found. • Red squirrel No signs of red squirrel including dreys were found. • Bats All trees within the survey areas have negligible roost potential.
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10 Options Assessment Report A816 Bealach Mor 2.3 Geology • A fault is marked on the map running along the east-west line of the existing A816, from the coast to Salachary, through Bealach Mor. Further faults are shown to the south as splay faults originating from the main fault orientated towards the southeast. Figure 3 – BGS geology map of the study area. Figure contains British Geological Survey materials © UKRI 2025 The geology though Bealach Mor differs notably to the north and the south of the A816 (Figure 3), due to the presence of the fault. The area is dominate by metamorphic rocks from the Tayvallich Volcanic and Slate and limestone Formations, and Crinnin Grit Formation
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11 Options Assessment Report A816 Bealach Mor (Neoproteozoic Era). Crosscut by Dalradian Supergroup - metagabbro and metamicrogabbro and North Britain Siluro-Devonian calc-alkaline andesite dykes. No mass movement, artificial ground or borehole records are recorded for the area. 2.4 Superficial deposits Figure 4 – BGS superficial map of the study area. Note the three landslides recorded for the 7th October 2023 event. Figure contains British Geological Survey materials © UKRI 2025.
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12 Options Assessment Report A816 Bealach Mor The BGS GeoIndex superficial layer (1:50,000) shows peat deposits in the lower lying areas within the valleys of the study area (Figure 4), the depth of these is not recorded but that they are present indicates they are substantial and likely to exceed 5m depth. There is also a deposit of raised marine deposit of sands and gravels on the former raised beach at the western end of the site. Alluvium deposits are indicated in the vicinity of the Kintraw Burn and from Lochan na Goirt. The majority of the soils within the area are shown on the Macaulay Institute for Soil Research (1:250,000) map as brown forest soils, humic gleys; some peaty gleys and peaty podzols, while there is a small band of soils close to the coastline shown as humus-iron podzols, peaty podzols. 2.5 Rockfall and landslide history No rockfall or landslide records were found for the area. There are three landslides recorded on the BGS GeoIndex (Figure 4), but these all relate to the 7th October 2023 event, no prior incidents are recorded from the site or nearby. 2.6 Archaeology Historic Environment Scotland records a Scheduled Monument (NM 83046 04974, Figure 5) for Kintraw Standing stone and cairns to the west side of the site and the east of the A816 in a field to the south of the Kintraw burn. Further protected sites are listed on Canmore within the area and are listed in Table 2 below. Figure 5 – Scheduled Monument site recorded by historic Environment Scotland shown in the red highlighted area. The red location pin denotes the location of the prehistoric fort recorded at the site on Canmore (Canmore ID 22850).
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13 Options Assessment Report A816 Bealach Mor Table 2 – Canmore / RCAHMS listed sites within the assessment area. Listed/ Protected Site Position relative to proposed routes Kintraw Farmstead (Period Unassigned), Lime Kiln (Period Unassigned) North of all proposed works areas Kintraw Bridge Road Bridge (18th Century) North of all proposed works areas Kintraw Ring Cairn (Neolithic) - (Bronze Age) Within the Scheduled Monument Designation Kintraw Cairn (Period Unassigned) Within the Scheduled Monument Designation Kintraw Platform (Period Unassigned) Within the Scheduled Monument Designation Kintraw Cairn(s) (Prehistoric), Enclosure (Period Unknown), Standing Stone (Prehistoric) Within the Scheduled Monument Designation Kintraw Fort (Prehistoric) Within area of the works – All routes widening the west end of the temporary bypass and routes around fort – Yellow, orange, green, red, grey. Kintraw Rig And Furrow (Medieval) - (Post Medieval) Close to A816, covered/destroyed by 2023 landslide. Barbreck (Farmstead) (Period Unassigned) Close to Grey Route Dun Na Ban-Oige Fort (Prehistoric) Close to Grey Route Kintraw Cairn (Period Unassigned), Cremation (Period Unassigned), Field System (Period Unassigned)(Possible) Out with area 2.7 Waterbodies • The Kintraw Burn to the north of the site is the main watercourse thought the site. All watercourses for the area drain to Loch Craignish, a sea loch located to the west of the site which opens to the Sound of Jura. • Loch Craignish (15.37km2) is a former designated shellfish growing waterbody, de- designated in 2012. • No designated waters are located within the study area. 2.8 Traffic data AADT values are provided in Table 3 below.
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14 Options Assessment Report A816 Bealach Mor Table 3 – AADT values for the A816. direction_of_travel pedal_cycles two_wheeled_motor_vehicles cars_and_taxis buses_and_coaches lgvs hgvs_2_rigid_axle hgvs_3_rigid_axle hgvs_4_or_more_rigid_axle hgvs_3_or_4_articulated_axle hgvs_5_articulated_axle hgvs_6_articulated_axle all_hgvs all_motor_vehicles 2013 Manual Count N 1 12 765 5 140 38 3 11 2 15 3 72 994 2013 Manual Count S 0 6 740 6 147 32 5 6 5 3 9 60 959 2022 Estimate N 1 11 680 4 211 44 4 15 3 13 3 82 988 2022 Estimate S 0 6 657 5 221 37 6 8 7 3 10 71 960 2.9 Social and economic context A recent report by Jacobs / AECOM for Transport Scotland :STPR2: Initial Appraisal: Case for Change - Argyll & Bute Region 2020 details much of the social and economic context for the area and the reader is referred to this more in-depth document for further information.
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15 Options Assessment Report A816 Bealach Mor 3 Option Generation 3.1 Overview This study examined numerous potential route options. Route corridors utilising long and/or remote areas from the A816 were rejected for further investigation and the option process since these did not meet the objectives of the project. The anticipated costs and potential environmental impacts of each route were considered disproportionate to the problems faced by the existing alignment of the A816. Eight options were taken forward for assessment. These range from a do minimum approach, utilising the existing A816 and bypass to a complete realignment of the road. Initially longer (>10km) options were proposed that would bypass the slopes and other potential future issues along the Bealach Mor stretch of the A816. These were discounted for further assessment in discussion with Argyll and Bute Council as beyond the scope and remit of the project. The following section summarises the options and presents the best assumptions of a route path / alignment, but it should be noted that changes or refinements may be required at a later stage of assessment. • Option 1: A816 (Purple Route) • Option 2 & 2a: A816 and bypass (Orange Route) • Option 3: A816 Realigned and bunded (Pink Route) • Option 4: Bypass with retaining wall/revetment (Yellow Route) • Option 5: Bypass with realigned turn (Blue route) • Option 6: Bypass and lower field (Green Route) • Option 7: Bypass around fort (Red Route) • Option 8: Alternative bypass (Grey Route) The last two of the options (Red and Grey Routes) considered require to passing through or very close to sites of archaeological significance (Scheduled Monument and Fort), these were deemed unlikely to gain necessary permissions and to carry a large risk of impact to programme or budget should works uncover archaeological significant finds, these were discounted from further assessment but remain included for completeness. An overview of the route option locations is provided on Figure 6 and individual routes are shown within the relevant tables below. 3.2 Cost estimates Previous upgrades of trunk road schemes recently completed in similar environments are listed below for comparison to the current proposed routes Costs are based on the available information and cover geotechnical investigation, design and construction. It is only possible at this stage without detailed route ground investigation and design to provide outline costings, these have been based on relatively pessimistic ground conditions. Land acquisition costs would be additional to the costs provided. Relocation of services are not factored within the cost estimates and may attract significant additional costs where required.
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16 Options Assessment Report A816 Bealach Mor Additional estimates have been provided to address further potential geotechnical hazards which if not addressed may result in road closure of the A816. There are two areas identified: • The lower embankment below the existing A816 (Figure 7) is overstep made ground with potential for failure and assessment is recommended with remediation if required, estimated at £1.5 - £2M. All the options pass over this area (with the exception of Green Route – Option 6). • There is a large tension crack (around 25m in length) noted on the slope above the A816 where the existing bypass meets the A816 (Figure 8). This is a surface expression of a larger instability, thought to be a larger slip feature affecting the carriageway. This will need to be stabilised/remediated to prevent ongoing damage to the road foundation and surface. There is also potential for further slope failure above the road at this location, remediation works is estimated at £1.5M. Figure 6 – Overview of the eight route options displayed on aerial imagery for the area. Purple (Option 1), Orange (Option 2), Pink (Option 3), Yellow (Option 4), Blue (Option 5), Green (Option 6), Red (Option 7) and Grey (Option 8). The location of the lower embankment discussed above is shown by the no1. while the tension crack/slip location is shown by the no2.
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17 Options Assessment Report A816 Bealach Mor Figure 7 – Aerial photograph (taken on the 17/07/24) showing the embankment below the A816 discussed in the text. Figure 8 – Aerial photograph (taken on the 17/07/24) showing the tension crack and slip area. Inset photograph of the tension crack from the bypass tie in looking south (taken 26/08/24). Lower embankment
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18 Options Assessment Report A816 Bealach Mor Detailed descriptions of the route options, cost estimates, engineering requirements, geotechnical considerations are included for each option in Tables 4 to 12 below: Table 4 – Purple Route, Option 1. Route Option 1: A816 – Do nothing (Purple Route) Description Keep existing arrangement (i.e. use of the A816 under single lane traffic controlled by traffic lights with on-road barrier in place and move traffic to the temporary bypass during adverse weather or events). • 460 m length Cost Estimate • £17,000 per month (£204,000 PA), dropping to £10,000 (£120,000 PA) after mains power is installed. Operational costs for A816 / bypass only any event clearance/remediation would be additional. • Not including repairs (if required) for below road steep embankment at north side and deep-seated slip to the west. Engineering Assessment • The existing and temporary road surfacing will need upgrading and the risk of closure of the A816 remains high. Increasing instability may result in closure and/or increasing risk to road users. • Ongoing TM / Install of permanent TM required. • Maintenance / clearance will be required following events. • Impact to the public on an ongoing basis with no resolution is highly likely. • The barrier installed was placed in the road to quickly resolve landowner consent issues, this is not the optimal placement, and the barrier placed was the largest appropriate for the availability of space and function. The barrier does not provide full protection of the area covered and the residual risk remains moderate. • Topography and road layout is such that the option would be of ongoing substantial cost, especially if repeated events occur. • High risk to keep open during heavy rainfall / storms or slope instability – move to bypass. Geotechnical Hazard • Hazard from the slope above remains, it is likely that ongoing maintenance costs will be high if ongoing from the geohazards of landslides and rock fall. There will be additional maintenance and clearance costs following events. • The on-road barrier offers protection only to a section approximately 100m in length. The remaining road to the east has
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19 Options Assessment Report A816 Bealach Mor no mitigation and may be impacted by landslide/debris flow or rock fall from above. • Impact to the public on an ongoing basis with no resolution is highly likely. • There is a large tension crack (around 25m in length) noted on the slope above the A816 where the existing bypass meets the A816. This is a surface expression of a larger instability, thought to be a larger slip feature affecting the carriageway. This will need to be stabilised/remediated to prevent ongoing damage to the road foundation and surface. There is also potential for further slope failure at this location. • Assessment of the lower embankment of the existing A816 is recommended is recommended due to this being overstep made ground with potential for failure. Environmental Assessment Minimal environmental impact as this utilises the existing road layout. Discussion/ recommendation Future events from the slope are highly likely. Incidents of intense rainfall are likely to increase because of climate change, this is expected to lead to more frequent and larger volume events. This is what has been observed at other landslide prone sites in Scotland, e.g. Rest and Be Thankful. The area is only partially protected from rock fall and landslide/debris flow as the in-road barrier does not run the full length of the slope vulnerable to instability. This option and the orange options have the highest ongoing costs. Table 5 – Orange Route 1, Option 2. Route Option 2: A816 and bypass (Orange Route 1) Description Move to gyratory flow arrangement (northbound traffic on bypass/ southbound traffic on A816) with roads as existing. • 890 m length Cost Estimate £5M - £6M
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20 Options Assessment Report A816 Bealach Mor Not including repairs (if required) for below road and west deep-seated slip Engineering Assessment • There are space restrictions at the north joining point and complications due to significant height differences from the bypass/A816. • To allow turning of HGV/long vehicles would need the whole road width. Roundabouts would potentially provide a logistical way to transition to the gyratory flow and allow the larger vehicles the space required. • In order to build to the west, significant volume of fill would be required to accommodate any widening. • Further acquisition of grazing land would be required. • Impact to the public on an ongoing basis with no resolution is highly likely. • Topography and road layout is such that the option would be of ongoing substantial cost, especially if repeated events occur. • Difficult to keep open during heavy rainfall / storms – move to bypass. • The barrier installed was placed in the road to quickly resolve landowner consent issues, this is not the optimal placement, and the barrier placed was the largest appropriate for the availability of space and function. The barrier does not provide full protection of the area covered and the residual risk remains moderate. • High risk to keep A816 open during heavy rainfall / storms or slope instability – move to bypass. If there are weather forecasts or events impacting the A816 traffic may need to be moved to the bypass (as Purple Route – Option 1). • Road closure or further temporary bypass would be required to accommodate the construction works. • Construction programme estimated at 8 months. Geotechnical Hazard • Hazard from the slope above remains, it is likely that ongoing maintenance costs will be high if ongoing from the geohazards of landslides and rock fall. There will be additional maintenance and clearance costs following events. • The on-road barrier offers protection only to a section approximately 100m in length. The remaining road to the east has no mitigation and may be impacted by landslide/debris flow or rock fall from above. • Impact to the public on an ongoing basis with no resolution is highly likely. • Assessment of the lower embankment of the existing A816 is recommended is recommended due to this being overstep made ground with potential for failure. • There is a large tension crack (around 25m in length) noted on the slope above the A816 where the existing bypass meets the A816. This is a surface expression of a larger instability, thought to be a larger slip feature affecting the carriageway. This will need to be stabilised/remediated to prevent ongoing damage to the road foundation and surface. There is also potential for further slope failure at this location. Environmental Assessment The orange route follows the previous by-pass road and at the western extent bends slightly southwest through a patch of semi-
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21 Options Assessment Report A816 Bealach Mor improved acid grassland and roadside scrub. The impact of the route would be low, with works restricted to the tie in sections. Discussion/ Recommendation Flow in this direction requires crossing of vehicles at both end tie ins. Roundabouts would be the best option to allow space for turning vehicles (especially HGV) southbound onto the bypass as a large swing is required. Roundabouts could also accommodate the crossing of traffic back onto the left at the east tie in. Future events from the slope are highly likely. Incidents of intense rainfall are likely to increase because of climate change leading to more frequent and larger volume events. There is a risk of injury, fatality to the travelling public or vehicle damage from landslide/debris flow or rock fall. The barrier in place lowers the hazard at locations covered but does not fully negate the potential for a serious incident at the site. The area is only partially protected from rock fall and landslide/debris flow as the in-road barrier does not run the full length of the slope vulnerable to instability. This option and the Purple Route have the highest ongoing costs. It is considered high risk to maintain the A816 open during potential instability if, as in Purple Route move to bypass is required, a method of switching traffic to two-way on bypass should be considered. Table 6 – Orange Route, Option 2a. Route Option 2a: A816 and bypass (Orange Route 2) Description Move to gyratory flow arrangement (northbound traffic on A816 / southbound traffic on bypass) with bypass & A816 upgraded at joining points to mitigate issues at northbound end of bypass. • 890m length Cost Estimate • £5 – 6.5M
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22 Options Assessment Report A816 Bealach Mor • Not including repairs (if required) for below road and west deep- seated slip Engineering Assessment • There are space restrictions at the north joining point and complications due to significant height differences and tight corner from the bypass/A816. • To allow turning of HGV/long vehicles southbound on the bypass at the north corner they need greater road width. Flow in these directions would be difficult to manage as HGV or longer vehicles need to swing out onto the opposite lane to make the turn. Road widening would be required to the west and/or traffic lights or similar installed to manage priorities. • In order to build to the west, significant volume of fill would be required to support any widening to accommodate widening. • Further acquisition of grazing land would be required. • Road closure or further temporary bypass would be required to accommodate the construction works. • Construction programme estimated at 8 months. Geotechnical Hazard • Hazard from the slope above remains, it is likely that ongoing maintenance costs will be high if ongoing from the geohazards of landslides and rock fall. There will be additional maintenance and clearance costs following events. • The on-road barrier offers protection only to a section approximately 100m in length. The remaining road to the east has no mitigation and may be impacted by landslide/debris flow or rock fall from above. • Impact to the public on an ongoing basis with no resolution is highly likely. • Lower slope and deep-seated slip are recommended to assessment / remediation. Environmental Assessment • The orange route follows the previous by-pass road and at the western extent bends slightly southwest through a patch of semi- improved acid grassland and roadside scrub. The impact of the route would be low, with works restricted to the tie in sections. Discussion/ Recommendation Flow in this direction is optimal at the east side of the route as it allows vehicles to remain on the ‘correct’ side of the road. At the west side without road widening, it requires traffic lights to holding northbound traffic to allow space for turning vehicles (especially HGV) southbound onto the bypass as a large swing is required. Future events from the slope are highly likely. Incidents of intense rainfall are likely to increase because of climate change leading to more frequent and larger volume events. The area is only partially protected from rock fall and landslide/debris flow as the in-road barrier does not run the full length of the slope vulnerable to instability. There is a risk of injury, fatality to the travelling public or vehicle damage from landslide/debris flow or rock fall. The barrier in place lowers the hazard at locations covered but does not fully negate the potential for a serious incident at the site. This option and the Purple Route have the highest ongoing costs.
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23 Options Assessment Report A816 Bealach Mor It is considered high risk to maintain the A816 open during potential instability if, as in Purple Route move to bypass is required, a method of switching traffic to two-way on bypass should be considered. Table 7 – Pink Route, Option 3. Route Option 3: A816 Realigned and bunded (Pink Route) Description • Move of the A816 approximately 5-10m to the north and construction of a large pit/bund structure (potentially with additional rock fall barriers on top) to protect the road. • 525 m length Cost Estimate • £5.5 - £6.75M • Not including repairs (if required) for below road £1.5M for additional deep-seated slip Engineering Assessment • The road would be moved north approximately 5-10m and a large bund constructed, approximately on the current A816 alignment. • Traffic flows could be maintained on the temporary road to assist the construction program. • Landslide/debris flow and rock fall risk will be lowered but may not be removed entirely. • There is an overhead power line that would require relocation that runs 205m along the approximate line of the proposed road to the south of the most southerly plantation block shown on the aerial image above. • Rock excavation required though the existing rock cut. • Construction programme estimated at 8 months Geotechnical Hazard • There is potential for rock fall and landslide/debris flow to impact the A816 and modelling would be required to determine if additional mitigation measures, such as rock fall/debris barriers were required in addition to the bund. • Peat deposits are shown on the BGS mapping (Figure 4) in the alignment, this may require additional foundation • Lower slope and deep-seated slip are recommended for assessment / remediation.
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24 Options Assessment Report A816 Bealach Mor Environmental Assessment The habitats adjacent to the pink route are semi-improved acid grassland and scattered trees including rowan (Sorbus aucuparia), Goat willow and Downy birch. Discussion/ Recommendation The relocation of the road to the north would allow space to construct bunds large enough to prevent debris from reaching the A816. There is an additional hazard of potential rock fall from the slope, this is from rock crags and rock pillars high on the slope and from eroding blocks from landslide scarps and eroding gully side walls. To mitigate this risk rock fall barriers are likely to be required along the top of the bunds. The presence of the overhead power lines along the south of the forestry block complicates this route option as the cost and agreements for moving this will add time and budget uncertainty, this cost is not included in the costing. Additionally, the Pink Route would incur ongoing maintenance costs, particularly following events, clearance and repair to the bund and fence would be required. Table 8 – Yellow Route, Option 4. Route Option 4: Bypass with retaining wall/revetment (Yellow Route) Description Widening and upgrade of the existing temporary bypass route. Removal of the sharp, steep corner and realignment of the joining to the A816. • 460 m length Cost Estimate • £3.75M - £5M • Further £2M for lower road, £1.5M for additional deep-seated slip Engineering Assessment • To remove the sharp corner and overly steep gradient at the north end of the bypass this section would be rerouted along the west side of the fort hill along the line of the former drove road. • This would require the construction of a retaining wall or revetment structure to support the road width required. • The retaining wall is likely to need to extend out to the centre of the existing road and it is probable that the lower slope would need additional strengthening works to support the additional weight.
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25 Options Assessment Report A816 Bealach Mor • Traffic management will need to be extended to accommodate the tie in on the north side. • Construction programme estimated at 8 months Geotechnical Hazard Deep-seated slips are recommended for assessment / remediation. Works to retain the lower slope below the existing A816 are likely to be required to support the additional weight of the road and revetment. Environmental Assessment This route follows the previous by-pass going through the plantation forest then is proposed to bend down towards the north before rejoining the A816 going through semi natural acid grassland (B1.2). Discussion/ Recommendation The main length of the route is based around widening the existing temporary bypass with the main engineering section where the bypass turns north along the former drove road. The change to alignment would allow the removal of the sharp corner and reduce the steep gradient on the transition between the A816 and bypass area. In order to support the road would require fill with a retaining wall/revetment estimated to extend to around the centre line of the current road. Additional works may be required to stabilise the lower embankment to support the additional weight. The yellow option requires some excavation at the corner area but much less than other options and the risk to programme and budget due to archaeology finds/permissions is considered less than other options requiring greater excavation close to archaeological features and more deviation from current road positions (e.g. Red Route, Grey Route, Blue Route). The overhead power line crosses the temporary bypass around the mid-section where the road exits the forest block and minor realignment/height change may be required. This is not included in the costing. The Yellow Route is considered favourable as it is lower budget and environmental impact than other options while addressing the sharp corner and gradient issues effectively. The road is moved away from the unstable slope and ongoing maintenance costs are lower than other options close to the unstable slope. Table 9 – Blue Route, Option 5. Route Option 5: Bypass with realigned turn (Blue Route) Description Widening and upgrade of the existing temporary bypass route. Removal of the sharp, steep corner by realigning the eastern side of the bypass to the south. • 405m length
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26 Options Assessment Report A816 Bealach Mor Cost Estimate • £5 - £6M • Not including repairs (if required) for below road, £1.5M for additional deep-seated slip Engineering Assessment • Significant excavation is required to accommodate this route. The height difference of the existing bypass and the A816 tie in point is approximately 3m (higher at the bypass). The ground in the centre of the mounded area the route is crossing is approximately 5m higher than the bypass, this would require substantial reprofiling to accommodate the area required for the turn. • There will still be a substantial corner on the route but the gradient and more favourable curve/turn. • Construction programme estimated at 5-6 months. Geotechnical Hazard • This option moves the road towards the main slope and within the run out for landslides/debris flows and rock fall. If the ground is levelled and lowered in height the road also becomes increasingly vulnerable to these hazards. • Assessment of the lower embankment of the existing A816 is recommended is recommended due to this being overstep made ground with potential for failure. • Lower slope and deep-seated slip are recommended for assessment / remediation. Environmental Assessment The blue route will go through a short section of semi-improved acid grassland and require a large volume of bedrock excavation. Discussion/ Recommendation The main length of the route is based around widening half of the existing temporary bypass with a new section of road turning to the south to accommodate a less tight turn back to the north and tie into the A816. The topography is elevated between the bypass and A816 tie in points, this will require large volume of excavation (assumed to be mostly rock). The extensive excavation is likely to require archaeological permissions for excavations and would possibly be controlled i.e. watching brief, controlled methodology and full archaeological excavation of any new find areas. Discovery of archaeology would increase price and affect programme.
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27 Options Assessment Report A816 Bealach Mor The Blue Route takes the bypass back towards the unstable slope and the excavation of the ground to accommodate the road increases the potential for large landslide/debris flow events to impact on the route. In comparison to the Yellow Route, the Blue Route is has greater residual risk from the slope, higher environmental impact and the alignment is less favourable for increased cost. The overhead power line crosses the temporary bypass around the mid-section where the road exits the forest block and minor realignment/height change may be required. This is not included in the costing. Table 10 – Green Route, Option 6. Route Option 6: Bypass and lower field (Green Route) Description Widening and upgrade of the existing temporary bypass route for the eastern section of the route. A new western section would be constructed from the corner of the • 580m length (approximately 190m of new road construction) Cost Estimate • £7M - £8.5M • Not require for below road £1.5M for additional deep-seated slip Engineering Assessment • Extensive volume/importation of material would be required for the construction of the new section of road across the field. There is a 30m height difference from the west corner of the A816 where the road would start to the tie in point on the existing bypass. • Requires land purchase of land currently used for grazing. • Off-line construction of the majority of the road. • Construction programme estimated at 7-8 months Geotechnical Hazards • Height difference would require large volume of fill to be placed, ground conditions would be required to be adequate to support the weight, there are some softer areas within the field where additional foundations engineering may be required. • Detailed ground investigation would be required for the new section of road.
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28 Options Assessment Report A816 Bealach Mor • Deep-seated slip is recommended for assessment / remediation, lower embankment works would be included within the works, wider embankment is not used by this option. Environmental Assessment This route starts off adjacent to dense scrub with gorse (Ulex europaeus) at its northern extent then passing through heavily grazed neutral grassland with Sheep’s fescue (Festuca ovina). Discussion/ Recommendation The Green Route is cost prohibitive due to the volume of imported fill required. There would be a large volume of road traffic required to transport the materials required and the option is considered low rating for sustainability. The project would also require a detailed ground investigation to be undertaken to inform the design process to ensure suitability. The embankment required would be much greater in scope than required for the Yellow Route. The route passes over heavily used grazing land which would be expensive and potentially protracted to obtain. The overhead power line crosses the temporary bypass around the mid-section where the road exits the forest block and minor realignment/height change may be required. This is not included in the costing. Table 11 – Red Route, Option 7. Route Option 7: Bypass around fort (Red Route) Description The red route passes along the existing bypass track at the eastern side for approximately 170m before heading northwards though the plantation forest for 205m and then around the north side of the fort and tying into the A816 at the north corner close to/within the Scheduled Monument. • 640m length Discussion/ Recommendation • £9.5M - £10.5M • No lower embankment works required, additional cost for remediation of deep-seated slip.
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29 Options Assessment Report A816 Bealach Mor Engineering Assessment • The red route passes to the east and north side of an identified prehistoric hillfort (Canmore ID 22850). Permissions for excavations in the area is likely to be denied or heavily controlled i.e. watching brief, controlled methodology and full archaeological excavation of any new find areas. • Western tie in is located within/close to the Scheduled Monument site and due to topography, there are no suitable alternative routes in the area. • Construction programme estimated at 12 months. Environmental Assessment • The red route passes through conifer plantation (A1.1.2) with both Sitka spruce and Larch and severe windblow before joining the grey route running through semi-acid grassland (B1.2) and ending at a band of dense scrub (A2.1). • The impact on the environment would be high as the approximately 480m of the route would be newly constructed. Discussion The tie in location at the western end of the site passes though/close to the Scheduled Monument and is unlikely to be granted permissions or with such stringent restrictions to be prohibitive. The route is additionally at high risk of price increase and programme delay potentially as result of any archaeological finds and/or conditions to pass around the fort and surrounding previously undisturbed areas. The land required for the route is currently plantation forestry and grazing land. Due to the archaeological restrictions, long section of new road and budget cost this option is discounted. The overhead power line passes northbound along the west side of the forest block and minor realignment/height change may be required. This is not included in the costing. Table 12 – Grey Route, Option 8. Route Option 8: Alternative longer bypass (Grey Route) Description • The grey route is the longest route considered and passes to the north of the existing bypass and main plantation blocks to pass around the north side of the fort and tying into the A816 at the north corner close to/within the Scheduled Monument. • 760m length
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30 Options Assessment Report A816 Bealach Mor Cost Estimate • £10.5M – £12M Engineering Assessment • The grey route passes to the east and north side of an identified prehistoric hillfort (Canmore ID 22850). Permissions for excavations in the area is likely to be denied or heavily controlled i.e. watching brief, controlled methodology and full archaeological excavation of any new find areas. • Western tie in is located within/close to the Scheduled Monument site and due to topography there are no suitable alternatives. • The grey route is the only route to avoid both the lower embankment at the west end of the site and the deep-seated slip at the east side. • The route has the longest new road construction length at 760m. Geotechnical Hazard • There are areas of very deep peat and marsh land that would require additional foundation stabilisation works. • Detailed ground investigation would be required along the route. Environmental Assessment • The grey route passes through marshy grassland, a ground water dependent terrestrial ecosystem (GWDTE) and as such is a protected habitat. • The impact on the environment would be high as the entire 760m route would be newly constructed. Discussion/ Recommendation Although the route avoids the deep-seated slip at the east side of the area by tying into the A816 further east the additional cost of building in the peat/marsh area combined with the protected status of the GWDTE area makes it likely that even if permissions could be gained to allow works the costs would be greater than those to remediate the slip. The tie in location at the western end of the site passes though/close to the Scheduled Monument and is unlikely to be granted permissions or with such stringent restrictions to be prohibitive. The route is additionally at high risk of price increase and programme delay potentially as result of any archaeological finds and/or conditions to pass around the fort. Due to the archaeological and environmental restrictions, long section of new road and budget cost this option is discounted.
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31 Options Assessment Report A816 Bealach Mor The overhead power line passes northbound along the west side of the forest block and minor realignment/height change may be required. This is not included in the costing.
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32 Classification: OFFICIAL References AADT Traffic https://roadtraffic.dft.gov.uk/local-authorities/44 Accessed 07/01/25 British Geological Survey (BGS), GeoIndex Onshore, https://mapapps2.bgs.ac.uk/geoindex/home.html, accessed 04/02/25 Jacobs AECOM. 2020. STPR2: Initial Appraisal: Case for Change - Argyll & Bute Region. Kendon, M., 2023. Exceptional rainfall in Scotland, 6 to 7 October 2023, s.l.: Met Office. Nature Scotland National Biodiversity Network Gateway https://data.nbn.org.uk/ Nature Scot Site Link. Preston, R., 2025 Bealach Mor. Preliminary Ecological Appraisal. Scottish Government Urban Rural Classification (Scottish Government 2016) 2. Overview - Scottish Government Urban Rural Classification 2016 - gov.scot Accessed 16/01/25 SNH National Landscape Character Assessment. LCT 043 - Upland Parallel Ridges - Argyll - Final pdf.pdf, 1:50,000 Republished in 2019 SNH Sitelink http://gateway.naturescot.gov.uk/sitelink/searchmap.jsp Accessed 07/02/25 Soil Survey of Scotland Staff (1981). Soil maps of Scotland at a scale of 1:250 000. Macaulay Institute for Soil Research, Aberdeen. Soil Survey of Scotland Staff (1981). Land Capability for Agriculture maps of Scotland at a scale of 1:250 000. Macaulay Institute for Soil Research, Aberdeen.